The present invention relates to magnetic heads used for reading and writing data from and to a magnetic recording medium and manufacturing methods thereof and, more in particular, it relates to a magnetic head suitable for perpendicular magnetic recording and a manufacturing method thereof.
In magnetic disk apparatus, data on a recording medium is read and written by a magnetic head. To increase the recording capacity per unit area of the magnetic disk, it is necessary to increase the areal density. However, a current longitudinal recording system involves a problem in that the areal density cannot be increased because of thermal fluctuation over the magnetization of the medium as recordable bit length is smaller.
Methods capable of solving the problem include a perpendicular recording system of recording magnetization signals in the direction perpendicular to the medium. The perpendicular recording system can use a giant magnetoresistive head (GMR head), a tunneling magnetoresistive head (TMR head) with further higher reading output, or a CPP (current perpendicular to the plane) type GMR head, which allows a current to flow perpendicularly to the film surface. On the other hand, it is necessary to use a single magnetic pole head for recording. Also in order to increase areal density, the perpendicular recording requires improving the track density and the linear recording density. To increase the linear recording density, it is necessary to improve the gradient of recording magnetic fields of the recording head. For this purpose, the recording medium is constituted as a dual layer structure in which a soft underlayer is provided as a lower layer. To increase the track density, it is necessary to provide the magnetic head with a finer and higher-accurate track width.
Further, since the magnetic disc drive provides a skew angle adapted to access the inner circumference and outer circumference of a disc, a problem arises of side writing depending on the shape of a main magnetic pole particularly in the perpendicular recording. To eliminate this problem, it is necessary that the width of the track width direction of the main magnetic pole is wider on the trailing side and narrower on the magnetic head substrate side, that is, has an inverted trapezoidal shape with respect to the substrate direction. For example, Patent Document 1 (JP-A No. 2003-263705) discloses an example of a magnetic head for use in perpendicular recording in which the lateral surface of the main magnetic pole is formed, by ion milling, into an inverted tapered shape by etching the main pole formed by a frame plating method. Patent Document 2 (JP-A No. 2004-95006) discloses a method of manufacturing a magnetic head for use in perpendicular recording, in which the surface of a substrate is obliquely irradiated with ion beams by using, as a mask, a non-magnetic metal film comprising Ta, W, Ti or an alloy thereof in order to form a write pole in an inverted trapezoidal shape.